Collet chuck



1945- R. E. HINES 2,410,344

COLLET CHUCK I v Filed Aug. 7, i944 2 Sheets-Sheet 1 Patented Oct. 29,1946 UNITED STATES PATENT OFFICE COLLET CHUCK Rufus E. Hines, Chicago,Ill. Application August 7, 1944, Serial No. 548,325

The present invention relates to collet chucks, and is particularlyconcerned with the provision of improved collet chucks for use withlathes or milling machines in production work. The present collet chuckis an improvement of the collet chuck shown in my prior application,Ser. No. 495,683, filed July 22, 1943, which has issued as U. S. PatentNo. 2,364,212, on December 5, 1944.

The present invention relates to collet chucks, and is particularlyconcerned with the provision of an improved collet chuck which isadapted to secure or to release the work piece while the chuck of thelathe or milling machine is still rotating, so that it is not necessaryto stop the machine when it is desired to remove one work piece from thechuck and to place another in the chuck.

It is well known that in production work the time consumed in stopping,decelerating, starting, and accelerating the machine is an importantfactor in thecost of the products made. In a machine operation requiringone or one and a half minutes, as much as one half minute may beconsumed when the work is finished, in bringing the chuck to a stop sothat the article may be removed from the chuck and another work pieceinserted in the chuck, and in bringing the chuck up toworking speedagain. The time so wasted is proportionally larger in operations whichrequire only a short period of machining than it is where the machiningoperations take a longer period of time. v

One of the objects of the present invention is the provision of animproved collet chuck of the type disclosed in my said priorapplication, in which the structures of the actuating member and the camwhich it supports are so arranged that the force which is applied to theclosing member is equally distributed and applied in an axial directionat three equally spaced points so that there is no tendency of theseforces to tilt or cook the closing member in any action diverging fromthe axial direction. I

According to the present invention, this is accomplished by a separatecamming member, which is mounted in a floating relation with respect tothe actuating fingers and the actuating member so that this cam may findits own posi tion in which all of the three fingers are equallytensioned and simultaneously actuated to bear the load equally when thecollet is closed.

In order to secure such an equal bearing of the load in the collet shownin my prior application very accurate machine work is necessary, andeach of the three fingers must be identical in 2 Claims. (Cl. 2 '7950) 2I size and shape and identically and symmetrically placed on thesupporting body; and it is another object of the invention to provide animproved structure by means of which such extreme accuracy in thelocation and construction of the fingers and cam are not necessary, sothat the chucks may be constructed with greater economy and equalaccuracy in the final support of the work in production.

In addition to these objects, the objects of the present invention aresubstantially the sam as those of my prior application, above mentioned.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the two sheets of drawings accompanying this specification,

Fig. l is a side elevational view, in partial section, of a collet chuckembodying the invention, and mounted upon the spindle of a lathe;

Fig. 2 is a full size and elevational view of the chuck, withitsactuating mechanism for securing andreleasing the work piece, theactuating'mechanism being mounted .on the bedof the lathe;

Fig. 3 is an exploded view in sideelevation and partial section, showingthe parts of the chuck in the order of their assembly;

Fig. 4 is a full size vertical sectional view of the chuck, taken on aplane passing through the axis of the spindle of the lathe.

Referring to the drawings, it] indicates in its entirety my improvedcollet chuck, which is shown in connection with the spindle nose of alathe. The collet chuck i0 is provided with a metal body i2, having anaccuratelyflmech ned, round, and polished outer cylindrical surface I3.

The metal body 12 is preferably carried by a supporting collar 14, whichmay beprovided with a cylindrical bore i6, adapted to receive with: atightl pressed frictional fit the reducedcylindrical portion I! ofthe-body l2.

This reduced cylindrical portionv i1 is separated from the cylindricalsurface l3, by an annular shoulder l8; and in some embodiments of theinvention the body 12 and the supporting member 14 may be one integralmember.

The reduced cylindrical portion I! is pressed into the bore l6 until theannular shoulder 18 engages the plane end I9 of supporting member 14.

The supporting member 14 is provided with the outer threaded surface I5and with a radially extending attaching flange 20 having an outercylindrical surface 2| and a plane annular face 30 on the supportingmember I4 and threaded collar 28 serve to assure theconcentricity-of-the chuck body with the threaded collar 23; The bolts24 pass through the flange 2n and arethre'aded into the bores 3| in thecollar 28.

Y the work by means of six lines of contact.

4 tered position, and a high degree of accuracy is attained by thischuck, as evidenced by measurement of the concentricity a short distanceout from the place where the chuck grips the work.

If the work piece happens to be slightly bigger than the bore 49 in thecollet, such as a few thousandths, then obviously the two cylindricalsurfaces of the collet and the bar will not fit perfectly, but thecollet willgrip the work at each of itslegs, the contact being at theedges of each slot 53 in the collet, effecting a grip of If 5 .the.stock happens to be smaller in diameter than the bore 49 of the collet,such as a thousandth,

There is preferably a clearance between the annular surfaces at thepoints 32, 33 so that the plane surface 22 of the attaching flange 29may engage the collar 28 without interference at the points 32, 33.- v

The collar 28 is adapted to. engage the dose .34 of a lathe spindlewhich is provided with threads at 35 for engaging the complementarythreads 36 in the collar 28, and the nose 34 and collar 28 are alsoprovided with the closely fitting cylindrical surfaces at 31 and theengaging plane surfaces at 38 to assure the firmi and concentric supportof the chuck body 42 en' -the .nose of the lathe spindla- The parts 12,I4, and-'28 are actually fitted and secured together before the grindingof the surfaces 31, i3, and other concentric surfaces of the .chuck, soas to assure concentricity of all of the surfaces of the chuck whichshould be so.

The chuck body 12 is provided with an accurately ground cylindrical bore39 terminating in an abrupt annular shoulder 40, for engagingcomplementary cylindrical surface 4| and plane end Body surface 42,respectively, onthe collet 43, 12 also has a through counterbore 44 for.passingthe work piece, and bore 44 maybe larger thanthe bore 49 .in' thecollet 43 so thatanumber of similar collets of different bore sizes 44may be used in the same chuck. 7

43 comprises an accurately machined and pol- .ished metal member havingan axial through bore 149,. which has a'close but sliding fit with awork .pieceof predetermined cylindrical shape and size; I

Like the collet in my prior application, above mentioned, the collet 43herein is intended to grip the Work or stock onlyat theright end of thegcollet in Fig. 4, over a predetermined length of the bore 49, whichisindicated by. thedistance between theright end of thecollet andtheshoulder '49a,'indicating thebeginning of a clearance.

There is a clearance 4% extending from 4911 to the seatedend of thecollet and a greater clearancefin the body 12 at the bore 44. Suchcollets are. provided in the proper size for round bars that are used inthem',and the clearance is necessary because suchv bars may vary a fewthouseindths in production in their diameters.

It will be evident that if the bar is exactly the same size as thecollet, its cylindrical surface would fit within the curvature. of thecywhndric'al gripping surfaces of the bore 49 on the collet. The lengthof these gripping surfaces is sufficient to hold the work firmly inaxially centhen obviously the cylindrical surface of the bar will notfit the cylindrical bore 49 in the collet because the bar is smaller;but there will be a line of contact between the bar and the colletmidway between the slots of the collet, effecting a grip by three linesof contact. 7

One ofthe most important advantages of the presentchuck is that it canbe used to grip a work piece, however short, and stock can be used updown to the very last end of the car, since the gripping takes placealong the bore 49 at the end of the collet wherework is beingdone.

In addition to the parts already described, the collet 43 also hasareduced cylindrical surface at its middle portion 5fl, and itpreferably has a larger head 5|. The head 5i has a frusto-conicalcamming surface 52, and the end of the collet, which carries theheadgthat is, the receiving end of the collet, has a plurality ofequally spaced, axial slots 53, which extend not only through the head5i, but backwardlyinto the body of the collet through the middle portion50 of the collet, stopping short of the cylindrical portion ll of thecollet. A

These slots 53 separate the receiving end of the collet 43 into threework gripping portions or jaws I54, and the length of the slots 53 issuch that the jaws 54 have a high degree of flexibility. Thus itrequires only a very small axial force to cause the jaws to grip'thework,

The closing member of the chuck -is'indicated by the numeral 55, and itcomprises a sleeve-like metal member having an accurately groundcylindricalbore 56 for engaging the cylindrical surface l3 on the bodyl2, with which the closing member telescopes. i At its forward end, thatis,

the right end in Fig. 4, the closing member has a radially and inwardlyextendingbody, which is 4 provided with a through bore 51, having afrustoannular flange 58, having an annular thrust surface 5!). Flange 58is small enough to be received 'in the bore 69 of the supporting cage SIfor the actuating fingers 52. The action of the closing member is thatas it slides inward, that is, toward the left in Fig. 4, conical surface5'! cams the conical surface 52 on the collet 43, and causes the jaws 54to contract and grip a work piece 63.

The accurately frusto-conical surfaces 52, 51 '(with respect to the axisof the chuck and spindle) align and support the receiving end of thecollet 43 in proper, axial position.

The cage member 6! comprises a substantially cylindrical metal memberhavingan internally 'threaded portion 64 for engaging the threads l5nLthe supporting member M of the body 12.

-By means of threads 15,64 the cage member 6| may have its axialposition adjusted as desired for the purpose of adjusting the grippingtension at jaws v54 and of the fingers 62, as will be further described.

Cage member 6| preferably has a threaded radial bore 65 for receivingthe slotted set screw '66, which engages member I4 to clamp the cage inany desired rotative and axial position on the body I2, I4.

The cage member BI is provided with a plurality, preferably three innumber,'equally spaced, axially extending slots in that end of the cagemember whichis toward the receiving end of the chuck, that is, the rightend in Fig. 4. These .slots have been indicated by numeral 51, and

each slot 91 is adapted to receive one of the pivoted fingers 99 whichare pivoted on the pins 69.

The pins 69 are mounted in the bores 19, which extend across the slots61 and are located at right angles to the radius which extends from theaxis of the chuck at the center of each slot. Each bore 79 alsocommunicates with a threaded bore 'II for receiving a socketed set screw12, which clamps the pivot pin 69 in place.

The fingers 68 are identical in construction, and each finger comprisesan elongated member, preferably constructed to spring steel, providedwith a bearing portion I3, a thrust shoulder I4, and an elongatedresilient and relatively slender arm 75, having a cam head I6 at itsend. The bearing portion 13 is an enlargement at the pivoted end of thefinger, having a transverse through bore H of cylindrical shape forreceiving the ivot pin 69 and serving as a bearing.

The thrust shoulder 14 is a radially extending surface or shoulder,located on the inner side of each finger, for engaging the thrustsurface 59 on the closing member 55. The bearing portion I3 may have asubstantially cylindrical edge surface extending from the thrustshoulder 74 and is of such size as to clear the inside of the unthreadedportion of the bore 18 in cage GI.

The arm portion of each finger 58 is made slender and elongated toincrease its resilient qualities, but it is also relatively stiff sothat the collet will grip the work piece firmly but resiliently. Thefingers may be provided with a plane surface I9 on each side, and with aplane surface 99 on that edge which is adjacent the closing member 55,which also clears the fingers at 8|.

The cam portion I5 of each finger 68. may comprise a small enlargementat the free end of each finger, having that side which is opposite tothe closing member 55 provided with a partially cylindrical surface 82.The size of this cam enlargement I9 is such that it may be received inthe annular groove 83, which is defined by the outer cylindrical wall 84of the closing. member 55,

the inner wall 85 of flange 39. on an actuating member 91, and the wallof the bore 89 in actuating member 81.

Each finger G8 is preferably provided with a plane end surface 89, whichis adapted-to serve as a stop surface, when it engages theinner surface85 on flange 86 of the actuating member 81. All of the other parts ofthe chuck may be made of tool steel.

The actuating member 81 may comprise a substantially cylindrical metalmember having a through bore 90 for slidably receiving the cage memberBI. At the receiving end of the chuck, that is, the right end in Fig. 3,the actuating member 81 is. provided with an annular shoulder 92 andasmaller cylindrical'counter-bore 93..

The bore and counter-bore 93 are adapted to receive the. floatingannular member 94, which servesmas a camming and retaining member andengages the. fingers 68. The floating member 94 has an externalcylindrical surface 95, which is of slightlysmaller diameter than the.bore 90 and external cylindrical surface 95, which is of slightlysmaller diameter than the bore 93, and it is provided, with the annularshoulder 9I that has a sliding engagement with the annular shoulder 92.a

The actuating member 81 is also provided with an annular groove I25. forreceiving the split steel ring I26 that springs into the groove I25v andprovides an annular shoulder for holding the floating member 94 againstthe annular shoulder 92.

The. split ring I26 is preferably rectangular, in cros section andcomplementary to the rectangular groove I25. The end member 94 also hasthe inner frusto-conical camming surface 98, leading to the inner wallsurface 88, the latter being adapted to serve as a retaining surface formaintaining the pressure on the fingers 68.

The radially inwardly extending flange 86 on the end member 94: servesto close that portion of the chuck against dust or shavings, and servestoprovide a stop surface to limit the axial movement of the actuatingmember toward the left in Fig. 4.

The radial flange 8B- is provided with a centrally located cylindricalbore 86a, which also has a clearance with respect to the closing member55 so that this flange does not interfere with the floating movement ofthe member 94.

The floating member 94 is adapted to move in its recess, sliding on thering I29 and the annularsurface 92 in such manner as is dictated by theforce which is applied to the ring by the fingers 58 as the floatingmember 94 is moved backward against the ends of the fingers.

Thefloating member 94 will take such a position that each of the threefingers 98 has the same force applied to it, and the closing member 55is actuated axially by an equal force applied to three equally spacedpoints on the'thrust surface 59. 1 The length of the actuating member 81is preferably such that it extends over the outer cylindrical surface 2!on the supporting collar 2|] so that this end of the chuck structure isalso closed against entrance of dust or shavings. The actuating member81 is also preferably provided in bearing portion I91, having a suitableball or roller bearing (not shown) for supporting the roller shaft I98.a

- The fork shaft M13 is rotatably mounted in the bearings I99 providedin the upwardly extending arms I 59 of a fixture I I l, which may haveitsbase plate H2, so formed as to fit upon the usual guidesv provided onthebed of a lathe, where the fixture may be seciued by means of athrough boltIIS. I

Fork. shaft; I93 is also provided with. a-crank fixture l4,' pinned tothe shaft I63, and having a bore for the cylindrical rod H5, providedwith a 'ball'llfi,and adapted to serve as an actuating lever 'ioro'pening or closing the chuck.

' Thehub Ill of the left fork arm I64 may be provided with a stop memberH8 for engaging another stop member I I9 carried by the adjacentupwardly extending arm 1 [Def the lathe fixture -l I I. These stopslimit theclockwise rotationof the lever. H5, and prevent'the lever Hfrom moving so far that the actuating member 81 might come oii thechuck; They also limit the range of movement of the lever H5 to arelatively small arc so that very little movement of this lever by theoperator is required to open or close the chuck.

Reference has been made to the threads I5, 64 to adjustthe axialposition of the cage member Bl, the adjustment being secured againstfurther movement by'set screw 66. The actuating member is provided withan aperture i2!) (Fig. 4) to permit access to the set screw 56, withoutremoving the actuating member 81.

Thethreads referred to permit a very fine adjustme'nt-of the position ofthe cage member 5| and hence of the fingers 68; and the fingers 68should preferably be so adjusted that they engage the thrust surface 59on the closing member 55,

adjacent the outer corner of radially extending -fiange 58, that is, asclose to pin 59 as possible.

.This increases the leverage of the fingers 68 on the closing member 55because it utilizes the shortest radius possible on the bell crank whichis represented by the thrust surface 14 on fingers "68andthe arm 15 ofthe finger 68.

The operation of the chuck is as follows: All of the concentric'surfaceson the parts of the :chuck are preferably ground so far as possible withthe parts assembled, so that the collet of the ."chuck' will hold thework piece 63 in accurately aligned axiallyrlocated position. The chuckis shown in closed position in Fig. 4. In this position thefingers haveentered the groove 83 in the actuating member 81, and the cam surfaces82 are engaged by the cylindrical wall 88 of the acatu'ating member 81.e

r 'In one form of the invention the surface 35 on -the member 28 is leftover-size so that the customer may place this member upon his lathespindle and turn it concentrically to fit the bore In "this position thefingers 68 exert only a pass into the bore,88, which acts as a retainingmember, the floating member 94 is also adapted to exert an equal holdingforce on all three of the fingers 68;

-' Since it has three-point contact with the fingers, and since it ismounted for'fioating move- -m'ent, the floating member 94 may assumesuch "a'position that'is required by the reaction of the "fingers 68against it I have discovered that with such a floating cam "the exactshape and size of the fingers and the exact location of their points ofpivot assumes less importance with respect to the accuracy of the chuck'bec'ause these factorsnolonger affect 'rAfter' the collet "has beenclosed and the fingers "8 'the'way.inwhichlforce. is applied to theclosing member 55.

With the present structure it is no longer so important that each fingershall be identically locatedand identical in shape and size; andtherefore the present chuck can be constructed at a lower cost and withgreater accuracy in the holding of the work, without such great care inmaintaining the accuracy of size and location of. th'efingers andadjacent parts. l

When the chuck is-closed, as shown in Fig. 4,

fingers 63, being resilient, are slightly bowed, and the thrust shoulder14 on each finger engages the flange 58 on the closing member 55 to,hold it in position as shown. Closing member 55 is in such positionthatits inner frusto-conical surface 51 holds the jaws 54 in engagementwith the work piece and in axial position with respect to the axis ofthechuck. When it is desired to open the'chuck, it is not necessary tostop the rotation of the chuck. .The operator needonly throw the leverH5 toward the right, that is, clockwise, through a small arc, and thefork arms I64, acting through the rollers Hi1, will move the actuatingmember 87 toward the right in Fig. 4.

As this movement takes place, the finger holding surface 88 of theactuating member 81 will pass off the fingers, and the fingers 68.willride outward on the camming surface 98 of the actuating member 81.

As the fingers 68 pivot outward, away from the closing member 55, thethrustshouldcrs 14 will move axially toward the right in Fig. 4,permitting the closing member 55 to move toward the right also. Theclosing member 55 is urged toward the rightin Fig. 4 by the resilientjaws 54 of the collet 43, which act on the camming surface 52 of theclosing member 55. This movement isquite small, but his foundthatrelease of the fingers immediately causes a release of the workpiece inthe collet.

Thus the operator need not lose the time incident to the stopping oftherotation of the chuck, but he need only throw the lever H5 in aclockwise direction to release the work piece .while the chuck isrotating, and then the work piece may be removed and another inserted.Movement of the lever H5 in the opposite direction, that is,counterclockwise, causes the chuck to grip the work piece while thechuck is still rotating, and the operator may then commence work on thework piece at once.

The closing of the chuck on the work takes place asfollowsr' Lever 5moves the shaft I63 and fork llllcounterclockwise, and the rollers mlmove the actuating member 81 toward the left to the position of Fig. 4.As this movement takes place, camming surface Men the actuating memberfil rides on the cams 82 of each finger, causing all three fingers topivot inward toward the closing member 55 at their free ends.

Due to the floating action of the member 94, equal force is applied toall threeof the fingers {53 during this camming action.

This pivotal movementof the fingers continues until the fingers havetheir cam ends in the groove 83', where the fingers are retained untilthe actuating member is once more moved toward the right from theposition of Fig: 4. As the fingers move pivotally inward, the thrustshoulders 14 on the fingers engage the annular thrust surface 59 on theflange 580i the closing member 55, drawing the closing membertoward theleft to the position ofl ig, 4'. l I

The closing member exerts a contracting action on the free end of thecollet, and causes the jaws 54 of the collet to grip the work piece, butthis contracting action takes place wholly in a radial direction, as thecollet cannot move inward, due to its engagement at its inner end withthe abrupt shoulder 50 in the body "l2 of the chuck. The chuck is thusadapted to grip the work without moving the work longitudinally.

As distinguished from the prior art devices, there is no advantage, inthe present device, in keeping the collet or the closing member fromrotating with respect to the rest of the parts of the chuck. The entirechuck is to be operated, at least most of the time, while-rotating.Therefore, the collet and the closing member are left free to rotate inthe assembly, and this causes the fingers 68 to come into engagementwith new surfaces, and prevents all the wear from taking place oncertain points of the closing member at the thrust surface 59.

It will thus be observed that I have invented an improved chuck whichmay be opened or closed without stopping the rotation of the chuck. Thischuck is peculiarly adapted to be used for pro duction work, where alarge number of work pieces of the same size are to be placed in thechuck successively for work of any kind.

Much time may be saved by the use of this chuck in production work byreason of this inherent capability of my chuck. In addition, the chuckis capable of very accurate Work, simple in construction and operation,and capable of use for a long period of time without necessity forrepair or replacement of any of its parts.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise details of theconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States, is:

1. In an actuating mechanism for a collet chuck incorporating a colletprovided with an axial bore, a locating surface at one end and a 10tapered peripheral surface at the other end, a supporting body having anaxial bore for receiving the collet and including a shoulder forlocating the collet axially thereof, a collet closing member slidablymounted for axial movement on.

said supporting member and having a tapered inner end surface coactingwith said tapered peripheral surface of the collet to urge the locatingsurface of the collet against said shoulder of the supporting body andto effect closing action of the collet, and said collet closing memberhaving a thrust surface opposed to the tapered inner and surfacethereof, the combination comprising,

a plurality of axially projecting fingers pivotally mounted incircumferentially spaced relationship on the supporting body and havingshoulders engaging said thrust surface of the collet closing member, achuck actuating member mounted for axial sliding movement on thesupporting body, said chuck actuating member having an integral internalradial shoulder in opposed relationship to the collet locating shoulderof said supporting member, and a floating camming member ofsubstantially less diameter than the chuck actuating member adjacentsaid shoulder carried by said chuck actuating member and having aninternal camming surface in position for coaction with the ends of saidprojecting fingers during axial movement of, the chuck actuating memberto effect axial movement of the collet closing member, said cammingmember being axially located relative to the chuck actuating member bysaid radial shoulder and against which it is movable radially relativeto the actuating member so that substantially equal force is appliedradially to each of said fingers, whereby to balance the forces appliedto said collet closing member.

2. The structure recited in claim 1, in which said chuck actuatingmember also has an internal annular groove spaced axially from saidradial shoulder, and a resilient split ring disposed in said annulargroove in the actuating member and projecting radially inwardly tooverlap said camming member, a

RUFUS'E. I-IINES.

